Power shovel dipper door latch



y 9 5- c. E. JONES 2,376,597

POWER SHOVEL DIPPEH DOOR LATCH Filed March 14, 1942 a Sheets-Sheet 1 I'NVENTOYR.

ATTORNEYS May 22, 1945. c. E. JONES 2,376,597

POWER SHOVEL DIPPER DOOR LATCH Filed March'l4, 1942 3 Sheets-Sheet v ATTORNEYS sYgg/MWY C. E. JONES POWER SHOVEL DIPPER DOOR LATCH May '22, 1945.

' Fil ed March 14-, 1942 s Sheets-Sheet a Y INVENTOR.

41M TTORNEYJ Patented May 22, 1945 UNITED snares OFFICE This invention relates to latch mechanism for the dumping door of a dipper, such as is used on power? shovelsandlike equipment.

. Ordinarily, a dipper doorlatch is adapted to be released by a power device which pulls a trip cableioperating through leverage so as to withdraw the latch from the latch keeper, thereby permitting tliedoor to open and the loadto be dumped, for instance into the dump body of a truck. iBecause of the considerable weight'of the load of material in the dipper, especially indippers of large capacity, a, very considerable force is required to release the latch.. In many cases, evenfthrough. the power-driven device, known as a dipper'trip, is employed, the required force has been so. great that compound or multiple lever systems have been used in the latch'operating mechanism, in order to give an increased mechanical advantage. Insome instances, a supplemental lever was arranged toward the bottom of the dipper stick, and in other cases such a supplemental lever was mounted on the bottom of the dipper door itself a I The foregoing expedients have proven troublesome and disadvantageous from a number 'of standpoints, including the fact that the installation or multiple levers is cumbersoma provides more points-for clogging with mud and freezing with water, and has resulted in excessive failures. Fouling of the operating mechanism onthe sides of dump bodies on trucks has also occurred.

One of the problems Which'haS been encountered in connection with the foregoing is-that the available space" on the dipperdoor for the mounting of operating parts is relatively limited, when considering the degree of mechanical advantage required from the operating leverage.

The present invention is particularly directed to the problems referred to above and,in accordance with theinvention, a single operatinglever is employed, lever being arrangedfto'provide the required high degree or pull for withdrawing the'latch The operating mechanism ofthi's' invention, including "said single lever, may readily'be installed the limited space available on thebottom of clipper dpgr, in a protected position; and the invention also contemplates a. mounting. bracket for the parts, configured to shield movingsurec mudan h li e: z

accordancewith another aspect of the invention, the several'parts of; the operating mechanism are 'arrangeldsd astopermitthe useLoflreljatiyelye large; fulcrum 11101115 in a, very confined A pucatmii March 14, 1942, seriall fo. 434,65?"

5 Claims. (01. 292 -186) space, thereby providing-fa constructionwhich is not only rugged, but which wears only very sicwiy.

A further object of the invention is the provision of a nov'el means for adjusting the position of the latch with reference to'the operating lever,

this mechanism beingconstructed to facilitate the making of adjustme'nts, as will further appear. Another purpose of the invention is to s'o forr'n and mount the'oper'ating lever and other parts as to provide proper latch closure by gravity, even without the aid of the usual closure spring. The invention also contemplates arrangement of the operatingleverage for the latch in 'a manner providing different degrees of mechanical advantage as between difierent parts of the stroke from 'latch-engaged to latch-release position. In accordance with this feature, the mechanical advantage' is at a maximuminthe initial portion of the release movemjent of the latch, the succeeding and latterportion of the inovementaffording a somewhat reduced mechanical advantag but providing a higher speed of release movemeri't. This'feature is of particular importance because of the fact that the'force required towithd'raw the latch frcmthe latch keeper is at a maximum at the start of'the stroke, and'ther'eaf ter diminishe's. Therefore, the total throw of the single operating lever need not be excessively long, 'not-' withstanding'the fact that an unusually high mechanical advantage is provided'for the initialportion of the release stroke.

'In accomplishing the foregoing, the invention contemplates the employment of a lever member and a link member pivotally interconnected, a latch bar, a pivotal connection between one of said members and said bar, and a fulcrum for the other of saidmembers, so that 'When the mechanism is operated oneof the pivots. moves inanrarc about the fixed center of the fulcrum, thereby accommodating the swinging motions of said members to the rectilinearmotion-bfthe latch..bar.. This arrangement also has the'ad- .va'ntageiof giving the desired variation in leverage at. different parts of the releasing stroke. The invention also provides means of adjustment ofthe geometrical relationship of certain of these parts, for example an adjustment in the ,efiective' length This can be utilized to adaptthe mechanismto difierent, dippers and difierent, doors; but. when .on'ce .mountedion adoor, normal. adjustments star .66 weargcan be madeatjthe linkmember; such a way as to shift the position of the latch bar relative to the operating lever, without shifting the position of said lever or its fulcrum, so that this lever will move between the same limits of throw and can, therefore, make full surface contact with the limiting stops, under difierentconditions of adjustment.

How the foregoing and other objects and advantages are attained will appear more fully from the following description, referring to the accompanying drawings, in which- Figure 1 is a bottom view of a dipper door with the improved latch operating mechanism of this invention applied thereto;

Figure 2 is an enlarged view of the latch operating mechanism as shown in Figurel;

Figure 3 is a view taken substantially as indicated by the line 33 on FigureQ';

Figure 4 is a view taken substantially as indicated by the line 4-4 on Figure 2; and

Figure 5 nd. 6 are frag nt r e tiona vie of details taken substanti lly as indicated by the lines 5-43 and 6-6, respectively, onFigure 1.

The dipper door plate appears at 6,;this plate having reinforcements such as indicated at 1, 8 and 9-9, the latter being extended beyond ,one

edge of the door to serve as hinges Ill-I by means of which the door is pivotally connected to the dipper. I

The latch bar H extends through guides such as indicated at l2, providing for sliding movement of the latch bar in a direction generally transverse to the lower edge of the door, the latch bar (when in eng ged position) usually projecting beyond the edge of the door, so as to cooperate with a keeper mounted on the dipper. As seen in Figure 3, the latch bar H is weighted by thickening, so as to aid in latching by gravity, and this thickening is on, the face of the bar toward th dipp r, door p at so tha a p ce is left for the inner arm of the clevis l9 and for the insertion of a cotter pin through the inner end of pivot 20.

h pe tin lever r t e latch. apnea-rs a l3, this lever being bifurcated atone end to provide a pair of prongs Hie-44 which are received between upper and lower plates -45 of a mounting bracket which is secured to "the door plate 6. A pivot pin it serves to pivotally interconnect the lever and the mounting bracket, the pin being retained in positionby means of a cotter l7 overlying the head of pin 16 and mounted in a boss Ila on the outer bracket plate I5.

It should be observed that the space between the plates l5-l5 of the mounting bracket is closed on two sides, as indicated at |5a-l5a. The side walls on these two sides cooperate with the plates Iii-i 5 to provide a closed pocket housing and protecting the pivot parts including pivot l6 already described, as well as other pivot parts mentioned herebelow.

Movement of the lever may be effected by the usual trip cable which may be connected with the free end of the lever by means of the apertured lug Is. This lug is located at the upper face of the lever and toward its outer face, so that (as seen in Figures 2 and 4) there is clearance for attaching the cable without fouling on the door plate 6. The lever 13 itself is weighted by thickening on its inner face, as shown, in a,

region adjacent the cable attachmentlug, which assures downward swinging of the lever, --even in the absence of a latch closure spring, when:the door is in a pendent position :such as illustrated latch-engaged position.

in Figure 1. This weighting of the lever is sufiicient to overcome the automatic tension which is normally imposed upon the trip cable by the power dipper trip to keep slack out of said cable at all times.

The latch bar H is coupled with the lever !3 by means of a link It) having a pivotal connection 20 with the latch bar. The pivot 20 passes through an elongated slot 252a formed in the latch bar, so that the latch may give when the door closes, without requiring raising of the operating lever l3.

- The link 19 is internally threaded to receive the threaded eye bolt 2|, these parts being fixed in position relative to each other by a lock nut 22. The eye of said bolt 2! projects between the prongs I l-l4 of the bifurcated end of lever 13, the parts being joined by a pivot pin 23. This pin is desirably retained in position by virtue of extension of plates l5 of the lever mountm bracket, as indicated at 24.

Swinging movement of the operatinglcver. may

.be guided by means of a strap 25 secured to blocks 26 which serve as stops limiting the throw of the. lever. These st ps are confi ured tohare extended surface contact with the thickened (weighted) portion of lever it, which extended contact is the same under all oonditionse-ethereby reducing wear at the contactsurfacesfbccausc there is no change in the throw of the lever or the point of its fulcrum dueto normal adjust ments of the latch, as will now appear. r

Adjustment of the latch may be effected cby withdrawing :pin connection 30 between latch bar H and link l9, whereupon the link l9 may be swung to one side as indicated atzl9a, inyvhich position the lock nut 22 is loosened and the link rotated aboutits threaded connection the eye bolt 2|. As will readily be seernthis willalter the position of the latch bar with reference :to the operating lever, and this mechanism may be used when it is desired to compensate .for weal of any of the latch or operatingparts, or :0f the latch keeper.

More extensive adjustments .of this latch assembly can be employed, if desired to alter the initial positions of the latch bar and operating lever, so as to suit installation on different doors.

Before considering the action of the operating lever and link, it is pointed out that the mechanism is compact and readily adaptedto fit in the limited space available on the bottom-of thedoor between the various reinforcing members-and other parts, such as the reinforcing bar 28 and the stop bracket 21, which latter serves as an abutment limiting opening movement of the door. Stop bracket 21 projects appreciably from the plane of the door plate whereas the latch operating mechanism does not project appreciably therefrom, in view of which the parts are well protected and will not undesirably foul on dump bodies'oftrucks or the like. 1

In considering the operation of the "mechanism, it is first pointed out that because of the usual position of the dipper and of itsfdoor, when-the'operator swings the dipper to close the door, gravity maybe relied uponto-move the lever l3 and the latch barll downwardlyinto This is the full -line position'of'Figures 1 and2.

In Figure 2, the dot-and-dashline- 13mb? the operating lever represents the 'latch releas position, as effected under the influenceof the-trip cable (not shown). Examinationioi Figure-2 MB show' that when the lever 13 islin latch eugaged position, the axis of pivot 23, interconnecting lever l3 and link 19, is located close to, though preferably just to the right of, line m:c representing the path of movement of the latch bar ll. When the lever is moved to the latch-release position, this pivot axis moves to the point are described by the axis of pivot 23 when moving from the position indicated at p to the position indicated at pl.

The structure as illustrated further has the following advantage. Since point p is located slightly to the right of line .r-m, and point pl slightly to the left of that line, the link I9 is always maintained approximately in alignment with the path of movement 12-4; of the latch bar ll. The direction of pull on the latch bar, therefore, is'always very close to the line az-x.

The difference between the mechanical advantage in different portions of the stroke of the operating lever may be altered by differently locating the axis .of pivot l6, so as to change the ratio represented by the distances y and z. Differences in effect may also be secured by differently locating the axis of pivot 23 with reference to pivot I6, or with reference to the line w-:r.

The preferred arrangement contemplates that when the parts are in latch-engaged position, not only is the lever arm from pivot center 23 to fulcrum 16 at its maximum leverage (i. e., the minimum effective distance y); but so also (or nearly so) is the lever arm of the lever l3 (represented by a line joining the lug center l8 and the fulcrum center 16), for the latter is then approximately perpendicular to the line of cable pull and to the line of pull upon the latch (which thus gives substantially the maximum effectiveness). In the release position, when the firstmentioned lever arm is at its minimum operating effectiveness (represented by the increased distance e), the effective leverage of the,arm between centers l8' and I6 is then also a minimum. In short, one lever arm has an angular lag with relation to the other (as in a bell-crank), and

' they are so disposed that their varying leverages co-act in the intended sense. At the same time, pivot pins of increased diameter can be employed, because, even though this requires increased distance between pivot centers (of pins l6 and 23), a more than compensatory increase in overall effective leverage at the commencement of the stroke is secured.

I claim: 1

1. For a dipper door latch assembly, a latch bar operating lever having a transverse pivot axis adjacent one end, about which the lever may swing downwardly by gravity when the dipper door is in a pendent position, actuating attachment means adjacent the other end of the lever, and weighting means on the lever near said attachment means, said weighting means being configured to form extended surfacing for abutment against complementary limiting stop means, whereby the weighting means serves also as a wear element.

2. In latch mechanism for dipper doors, the combination of a latch bar movable generally transversely of an edge of the door, a latch bar operating lever adapted'to be operated to release the latch bar by an actuating cable connection or the like movable in a path generally paralleling the path of movement of thelatch bar, means mounting the lever for angular movement through a range in which the mid-position is substantially perpendicular .to the path of movement of the latch bar, and a pivotal connection between the lever and the latch bar comprising a pivot angularly movable with the lever in an arcuate path in which the mid-position is angularly ofiset from the mid-position of the lever to provide a substantial component of the initial portion of the release movement of the pivot in a direction transverse the path of the latch bar, while the major component of the final releasing movement of said pivot is substantially parallel to said path of the latch bar.

3. A construction in accordance with claim 2 in which the pivotal connection between the lever and the latch bar further comprises a link having a pivotal connection with the latch bar to accommodate the component of movement of said first pivot in a direction transverse the path of the latch bar. a

4. A construction in accordance with claim 2 in which the pivotal connection between the lever and the latch bar further comprises a link one end of which is pivotally connected with the lever by said first mentioned pivot, and a second pivot interconnecting said link and the latch bar, said two pivots'having their arms parallel to each other to accommodate the component of movement of said first pivot in a direction transverse the path of the latch bar.

5. For a dipper door latch assembly, a latch bar, an operating lever having a transverse pivot axis adjacent one end, about which the lever may swing downwardly by gravity when the dipper door is in a pendent position, actuating attachment means adjacent the free end of the lever, pivot means connecting the latch bar with the operating lever at a point nearer to the pivoted end of the lever than to the free end thereof, and weighting means on the lever concentrated at a point nearer to the free end thereof than to the pivoted end thereof.

CECIL E. JONES. 

